1. Field of the Invention
The present invention is directed to an apparatus for lighting highway signs, and in particular to remote fiber optic lighting apparatus for the illumination of reflective sign faces on overhead highway sign structures.
2. Description of the Prior Art
The importance of lighting highway signs to aid in navigation and for safety concerns cannot be over emphasized. Overhead highway signs are made with panels surfaced with reflective sheeting, such as manufactured by Minnesota Mining and Manufacturing Corporation of St. Paul, Minn. Reflectively surfaced signs are used worldwide and provide for improved visibility, especially at night. Signs placed along the side of the road, such as in two lane roads, do not need to be lighted as they generally fall within the range of most vehicles' headlights. However, with multiple lane roads, overhead signs are often required. These signs must be placed high enough to allow traffic to proceed safely under the sign and therefore generally are not well lit by most vehicles' headlights. The problem is greater when low beam headlights are used. Therefore, at night, and during other periods of poor weather, the signs must be illuminated.
Typical overhead sign lighting currently used is very cumbersome and requires much maintenance. Overhead sign structures include types known as sign bridge, cantilever, sign bridge cantilever, balanced butterfly, unbalanced butterfly, structure mounted sign, or more broadly sign support structures. Structure mounted signs are signs fastened to structures mounted on bridge overpasses. Standards for these signs are provided by the American Association of State Highway and Transportation Officials (AASHTO) and their publication entitled "Standard Specifications for Structural Supports for Highway Signs, Luminaries and Traffic Signals." The large light fixtures presently used for illumination require added structural components for their support which adds to the weight and cost of the underlying structure. Standards are also provided for the additional structural members to service the lights, such as catwalks for workers replacing the lamp bulbs. Performing maintenance causes an interruption in traffic because of traffic lane closures while maintenance is being performed. Due to the expense involved and the problems with closing lanes to perform maintenance, proper maintenance will often not be performed, resulting in signs which are not illuminated and often remain dark for extended periods of time. Such lack of illumination is hazardous and inconvenient to motorists. This situation is common throughout the world.
Efforts to overcome the shortcomings of lighting reflective signs panels have not been entirely successful. Light emitters, having tubular arrangements with light extending toward the signs, may provide adequate lighting for the reflective signs panels, but still require structure for supporting the light emitting tubes. In addition, the tubes require maintenance of the light source which is placed next to the sign, so that ladders or catwalks must be used to allow workers near the sign faces.
It can be seen then that an apparatus is needed which provides adequate lighting for reflectively surfaced sign panels. It can be further appreciated that such an apparatus should provide for servicing from ground level and for reliable lighting requiring minimal maintenance. Such an apparatus should also provide for the elimination of catwalks and other structures required for maintenance of the lighting. The present invention addresses these as well as other problems related to lighting reflectively surfaced sign panels.